Rotatable valve assembly

ABSTRACT

Rotatable valve assembly includes a mounting mechanism for rotatably mounting the valve in a housing, the mounting mechanism including a shaft having an outside end extending through the housing. A conversion mechanism converts fluid pressure in the housing into torque exerted on the shaft. A release mechanism is located outside the housing for preventing rotation of the shaft and valve when the torque exerted on the shaft is below a selected magnitude. The release mechanism allows the shaft to rotate when the torque exerted on the shaft exceeds a selected magnitude. A seal is provided for sealing the gap between the housing and the valve in the closed position. The seal has a first portion secured to the housing on a first side of the rotational axis of the valve, a second portion secured to the valve on a second side of the rotational axis, a first transitional portion coinciding with the rotational axis, and a second transitional portion coinciding with the rotational axis. The seal is unsecured to the valve or the housing and the transitional portions so that the seal may flex in the transitional portions as the valve rotates between the closed position and the open position. The first and second portions of the seal define a seal plane in the closed position of the valve and the second portion of the seal moves out of the seal plane with the valve when the valve is moved out of the closed position.

This is a divisional of co-pending application Ser. No. 08/519,653 filedon Aug. 25, 1995.

BACKGROUND OF THE INVENTION

The present invention relates to rotatable valve assemblies and moreparticularly, but not by way of limitation, to a rotatable valveassembly which may be used as a pressure relieving device.

The use of various sorts of rupture disks and pressure relief valves toprevent overpressure of a fluid pressure containment structure areknown. For example, U.S. Pat. No. 3,472,284 (Hosek) discloses a pressureseal in which disks 26, 32 rotate about offset shaft 24. A diaphragm 14is clamped between the disks and housing to seal the assembly and thediaphragm is sheared by the rotation of the disks when a desired fluidpressure is present. In order to reseal the valve, the housing members10, 12 must be opened and the valve taken out of service.

U.S. Pat. No. 3,039,482 (Goldberg) discloses a butterfly-type valve inwhich the longitudinal axis of the inlet and the longitudinal axis ofthe outlet are offset so that when the valve is forcibly oscillated andthe hermetic sealing sheet 13 is sheared, the sealing ring 18 on thelower edge of the valve 16 will safely clear the rough and sharp shearededge of sheet 13. The inlet and outlet body sections 11, 12 must betaken out of service and opened in order to reseal the valve after apressure relieving event.

U.S. Pat. No. 2,304,491 (Allen) and U.S. Pat. No. 3,603,333 (Anderson)disclose traditional right-angle relief valves in which a shear pin isused to hold the valve in a closed, sealed position until a preselectedpressure is experienced in the inlet to the valve. Upon overpressure,the valve shears the shear pin and is moved to an open, pressurerelieving position. Since both of these valves use a shear pin, thetolerances between the member holding the shear pin stationary and themoving member which shears the shear pin are critical to provide apredictable relief pressure. For example, referring to the Allen patent,the diameter of the stem 8 and the internal diameter of the bushing 9through which the pin 13 passes must be carefully matched to achieve anaccurately predictable shear pressure. As the space or gap between thesides of the stem 8 and the internal diameter of the bushing 9increases, the force required to shear the pin 13 diminishes rapidly.This requires precision matching and matching of the componentry that isdifficult and expensive to repeatably produce and to maintain. Othershortcomings of the right-angle relief valves include the increased bodysize and the flow restriction created by the right angle turn in theflow passageway, as well as the tendency of the valve to flutter orchatter on the seat during pressure fluctuations because the valve mustresist the entire fluid pressure exerted at the inlet, i.e., the shearpin and spring must directly resist the full force exerted on the faceof the valve by the inlet pressure and directly absorb all pressurefluctuations.

It is known to use rupture disks, such as reverse buckling rupturedisks, to replace right-angle relief valves. Rupture disks have a lowercost per unit of capacity when compared to right-angle relief valves.However, rupture disks must be taken out of service to restore theirpressure containing capability after a pressure relieving rupture. Thisrequires either a redundancy (the use of multiple rupture disks inparallel), shutting down the system, or risking exposing the system tooverpressure while the rupture disk is being replaced.

It is known to use rotatable valve assemblies, such as butterfly valves,ball valves, plug valves, and the like, to control or relieve fluidpressure in fluid containment systems. However, the prior rotatablevalve assemblies known to the applicants typically require that thevalve disk, ball, or plug, wipe or drag across a high friction, tightfitting seal made of elastomer or Teflon®. Therefore, a high torque isrequired to open the prior valve assemblies, and this torque increaseswith time while the valve is in a closed position.

Therefore, there is a need for a valve assembly which will provide fluidpressure relief at an accurately predictable relief pressure and whichmay be returned to its pressure containing state after a pressurerelieving event without taking the apparatus out of service. There isalso a need for a rotatable valve assembly which will reduce thefrictional forces which must be overcome to rotate the valve between theopen and closed position and in which the torque required to initiaterotation of the valve does not increase as the valve is left in a closedposition for extended periods of time.

SUMMARY OF THE INVENTION

The present invention is contemplated to overcome the foregoingdeficiencies and meet the above-described needs. In accomplishing this,the present invention provides a novel and improved rotatable valveassembly.

The invention is a rotatable valve assembly which includes a housinghaving an inlet and an outlet defining a fluid passageway through thehousing; a valve located in the passageway which is rotatable between aclosed position and an open position; mounting means for rotatablymounting the valve in the housing, the mounting means having a shaftwith an outside end extending through the housing which is rotatablewith the valve; conversion means for converting fluid pressure in thehousing into torque exerted on the shaft; and release means, locatedoutside the housing for preventing rotation of the shaft and valve whenthe torque exerted on the shaft is below a selected magnitude and forreleasing the shaft in order to allow rotation of the shaft and valve tothe open position when the torque exerted on the shaft exceeds aselected magnitude.

Preferably, the release means is a deformable means extending betweenthe shaft and housing in order to prevent rotation of the shaft, thedeformable means deforming or rupturing to allow rotation of the shaftand valve to the open position when the torque exerted on the shaftexceeds a selected magnitude. The deformable means may be a pin or beamwhich ruptures or which bends to allow rotation of the shaft and valve.In another embodiment, the release means is a magnetic catch whichprevents rotation of the shaft until the torque exerted on the shaftexceeds a selected magnitude.

In another embodiment, the housing includes a housing seating surfacehaving an inner peripheral edge extending around the passageway and thevalve includes a valve seating surface having an outer peripheral edgeextending around the valve. The housing and valve seating surfaces areabout coplanar and define a gap between the inner peripheral edge of thehousing seating surface and the outer peripheral edge of the valveseating surface in the closed position of the valve. A seal is providedfor sealing the gap between the seating surfaces and preventing flowthrough the passageway in the closed position of the valve.

The seal has a first portion secured to the housing seating surface on afirst side of the rotational axis of the valve and extending across thegap toward the valve seating surface; a second portion secured to thevalve seating surface on a second side of the rotational axis andextending across the gap toward the housing seating surface; a firsttransitional portion coinciding with the rotational axis; and a secondtransitional portion coinciding with the rotational axis. The seal isunsecured to the valve and the housing in the transitional portions sothat the seal may flex in the transitional portions as the valve rotatesbetween the closed position and the open position.

The first and second portions of the seal define a seal plane in theclosed position of the valve and the second portion of the seal movesout of the seal plane with the valve as the valve rotates from theclosed position to the open position. Preferably, the rotational axis ofthe valve lies in the seal plane in order to prevent undue distortion ofthe seal as the valve rotates between the open and closed positions. Theseal greatly reduces the torque required to open the valve, regardlessof whether the rotational axis of the valve lies in the seal plane, andthe seal may be used advantageously with the rotational axis of thevalve displaced from the seal plane. Also, the seal may be usedindependently of the conversion means and release means in virtually anyrotatable valve assembly.

It is an advantage of the present invention to provide a rotatable valveassembly which will open at a predictable and repeatable torquemagnitude, regardless of the length of time the valve has been in theclosed position.

It is an advantage of the present invention to provide a seal for arotatable valve assembly which allows the valve assembly to be opened ata predictable and repeatable torque magnitude.

It is an advantage of the present invention to provide a pressurerelieving rotatable valve assembly which may be reset or restored to apressure-containing condition without opening the assembly or taking theassembly out of service.

It is an advantage of the present invention to provide a pressurerelieving rotatable valve assembly which will automatically reset to apressure-containing condition without opening the assembly or taking theassembly out of service.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly which reduces the forces the valvemust resist and transmit to remain closed.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly which will replace traditional reliefvalves at a substantial cost savings and using a smaller valve housing.

It is an advantage of the present invention to provide such a pressurerelieving rotatable valve assembly in which a large diameter butterflyvalve may be used in relatively high pressure applications and using arelatively small rupture pin or magnetic catch to determine the pressureat which the butterfly valve will open.

It is an advantage of the present invention to provide such an assemblywhich improves the ability of the rotatable valve to be repeatedly resetto the same relieving pressure.

It is an advantage of the present invention to provide such an assemblywhich allows the valve to be repeatably reset without replacement parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by reference to theexample of the following drawings:

FIG. 1 is a view along line 1--1 of FIG. 3.

FIG. 2 is a schematic end view of an embodiment of the invention.

FIG. 3 is a schematic end view of an embodiment of the invention.

FIG. 4 is a schematic left side view of an embodiment of the releasemeans of FIG. 2.

FIG. 5 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 6 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 7 is a schematic left side view of another embodiment of therelease means of FIG. 2.

FIG. 8 is an elevational end view of the rotatable valve assembly of thepresent invention.

FIG. 9 is a view along line 9--9 of FIG. 8.

FIG. 10 is a view of FIG. 9 showing the valve in a partially openedposition.

FIG. 11 is an elevational view of the inlet face of an embodiment of theseal of the present invention.

FIG. 12 is a view along line 12--12 of FIG. 8.

FIG. 13 is an enlarged detail view of the first portion of the seal withthe valve in the closed position, as indicated on FIG. 9.

FIG. 14 is an enlarged detail view of the second portion of the sealwith the valve in the closed position, as indicated on FIG. 9.

FIG. 15 is a rear elevational view of FIG. 8.

FIG. 16 is a schematic side view of an embodiment of the reclosure meansof the invention.

FIG. 17 is a schematic side view of another embodiment of the reclosuremeans of the invention.

FIG. 18 is a schematic side view of another embodiment of the reclosuremeans of the present invention.

FIG. 19 is a plan view of the reclosure means of FIG. 18.

FIG. 20 is an enlarged, top-sectional view of the release means of FIGS.1 and 3.

FIG. 21 is a side elevational view of another embodiment of the releasemeans of the present invention.

FIG. 22 is an end elevational view of the release means of FIG. 21.

FIG. 23 is a top plan view of the lever arm of FIGS. 21 and 22.

FIG. 24 is a front elevational view of another embodiment of the releasemeans of the invention.

FIG. 25 is a top plan view of an embodiment of the release means of FIG.24.

FIG. 26 is a top plan view of another embodiment of the release means ofFIG. 24.

FIG. 27 is a top plan view of another embodiment of the release means ofFIG. 24.

FIG. 28 is a top plan view of another embodiment of the release means ofFIG. 24.

FIG. 29 is a cross-sectional view of the extrusion from which the sealof FIG. 11 is made.

FIG. 30 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 31 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 32 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 33 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 34 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 35 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 36 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 37 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 38 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 39 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 40 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 41 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 42 is a cross-sectional view of another embodiment of the seal ofthe present invention.

FIG. 43 is a side-sectional view of an embodiment of a vacuum reliefmeans for the rotatable valve assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will now be described withreference to the drawings. Like reference numerals or characters referto like or corresponding parts throughout the drawings and thedescription.

FIGS. 1-43 present embodiments of the rotatable valve assembly,generally designated 20, of the present invention. Although a preferredembodiment of the rotatable valve assembly 20, described herein tofacilitate an enabling understanding of the invention, is used as apressure relieving device which may be used to replace rupture disks,reverse buckling rupture disks, right angle relief valves, and the like,it is intended to be understood that the invention may be adapted tomany fluid pressure and flow control applications, as would be known toone skilled in the art in view of the disclosure contained herein.

Referring to the example of FIGS. 1 and 2, the assembly 20 may begenerally described as including a housing 22, a valve 24, mountingmeans 26 for rotatably mounting the valve 24 in the housing 22 about arotational axis 28, and power means 30 for rotating the valve 24 betweena closed position 32 and an open position 34. In the more preferredembodiments, the power means 30 comprises conversion means 36 forconverting fluid pressure in the housing 22 into torque exerted on ashaft 38, and the assembly 20 includes release means 40 located outsidethe housing 22, for preventing rotation of the shaft 38 and valve 24from the closed position when the torque exerted on the shaft 38 isbelow a selected magnitude and for releasing the shaft 38 in order toallow rotation of the shaft 38 and valve 24 to the open position 34 whenthe torque exerted on the shaft 38 exceeds a selected magnitude.

The housing 22 has an inlet 46 and an outlet 48 defining a fluidpassageway 50 through the housing 22. The inlet 46 of the housing 22receives fluid and pressure from a fluid pressure source (notillustrated), such as a vessel or piping. In the more preferredembodiments, the shaft 38 has an outside end 52 extending through thehousing 22 and the shaft 38 is rotatable with the valve 24 about therotational axis 28.

The preferred release means 40 includes deformable means 54 for makingdeformable contact between the housing 22 and the shaft 38. Thedeformable means 54 may be a pin, beam, bar, plate, disk, spring, orcomparable rupturable or deformable structure. The deformable means 54may be a permanently or irreversibly deformable structure, such as a pinor beam which bends or ruptures. In the prototype assembly 20, thedeformable means 54 makes deformable contact between the outside 56 ofthe housing 22 and an outside end 52 of the shaft 38. By outside 56 ofthe housing 22 is meant an area of the housing 22, or connectiontherewith, which is not exposed to or in direct operating contact withthe fluid contained inside the housing 22; and which may be accessedwithout opening the housing 22 and exposing the fluid contactingportions of the housing 22 to the outside atmosphere, and without takingthe assembly 20 out of service.

Referring to the example of FIG. 3, in one embodiment the mounting means26 includes a shaft 38 having a second outside end 58 extending throughthe housing 22; and the release means 40 includes a second deformablemeans 60 for making deformable contact between the housing 22 and theshaft 38, as previously discussed. The shaft 38 may be a single,continuous shaft extending across a face of or through the valve 24, ormay be one or more shaft ends, axles, ears, or the like which extendfrom the valve 24 through the housing 22. Limit switches, motiondetection switches, or the like may be provided at either or bothoutside ends 52, 58 of the shaft 38 to indicate whether the valve 24 isopen or closed or has been open or closed.

Referring to the example of FIG. 2, the deformable means includes a pin54, connected between the shaft 38 and the housing 22, which breaks whenthe torque exerted on the shaft exceeds a selected magnitude. Referringto the example of FIG. 4, in another embodiment, the deformable means 54includes a pin 54, connected between the housing 22 and the shaft 38,which bends when the torque exerted on the shaft 38 exceeds a selectedmagnitude. FIG. 4, also exemplifies a pin or spring 54 which isconnected between the shaft 38 and housing 22 so that the pin 54 isplaced in compression by the torque exerted on the shaft 38. Referringto the example of FIG. 5, the pin or spring 54 is connected between theshaft 38 and housing 22 so that the pin 54 is placed in tension by thetorque exerted on the shaft 38. Referring to the example of FIG. 6, thepin 54 is connected between the shaft 38 and the housing 22 so that thepin 54 is subjected to shear forces by the torque exerted on the shaft38.

FIGS. 2 and 4-7 are simplified, schematic illustrations of exampleembodiments of the release means 40. In the example of FIGS. 2 and 4-6,the release means 40 includes a contact arm 66 having a first end 68connected to the outside end 52 of the shaft 38 and a second end 70extending from the shaft 38; a release support 72 connected to thehousing 22; and a pin or spring 54, connected to the release support 72and obstructing rotation (clockwise in FIGS. 2 and 4-7) of the secondend 70 of the contact arm 66. The pin or spring 54 obstructs or preventsrotation of the contact arm 66, shaft 38, and valve 24 from the closedposition 32 of the valve until the torque exerted on the shaft 38exceeds the selected magnitude.

FIGS. 4-7 are simplified, schematic illustrations of additional exampleembodiments of the release means 40 as seen from the left side of FIG.2. Referring to the example of FIG. 4, the pin or spring 54 is disposedon the release support 72 so that the pin is subjected to compressiveforces by the second end 70 of the contact arm 66. This type of pin 54is sometimes referred to as a buckling pin or, if it is a spring, acompression spring. The pin or spring 54 should be secured between therelease support 72 and the second end 70 of the contact arm 66 so thatthe contact arm 66 holds the valve 24 solidly in the closed position 32.The pin 54 should also be secured so that when the pin 54 buckles (orthe spring compresses), it does not interfere with the clockwiserotation of the contact arm 66 and valve 24 from the closed position tothe open position. For example, in the embodiment of FIG. 4, the firstend 62 of the pin or spring 54 may be fastened securely to the releasesupport 72 with the second end 64 of the pin simply contacting thesecond end 70 of the contact arm 66 or being received in a recess 71 inthe second end 70 of the contact arm 66 so that the second end 64 of thepin 54 is easily detached from connection with the contact arm 66 whenthe pin 54 buckles or bends.

Referring to the example of FIG. 5, the pin or spring 54 is connectedbetween the release support 72 and the second end 70 of the contact arm66 so that the pin is placed in tension by the contact arm 66. This typeof pin 54 may be referred to as a tension wire or, if it is a spring, atension spring. The preferred tension wire or spring 54 has a first end62 which is secured, such as by clamps, bolts, screws, or the like tothe release support 72 and a second end 64 which is secured, such as byclamps, bolts, screws, or the like to the contact arm 66. Alternatively,a perforation or hole may be made in the contact arm 66 and/or releasesupport 72, the perforation being large enough to pass the tension wirewith the appropriate end(s) of the tension wire being enlarged orfastened so that it will not pass through the perforation when the wireis placed in tension. Referring to FIG. 5, as the valve and contact arm66 rotate clockwise from the closed position to the open position, thewire or spring 54 is placed in tension until the torque exerted on thevalve 24 and wire 54 exceeds the selected rupture pressure of thetension wire 54 or the restraining force of the tension spring. As inthe other embodiments of the release means 40, the tension wire orspring 54 should be connected between the contact arm 66 and releasesupport 72 in such a manner that the valve 24 is held securely in aclosed position.

Referring to the example of FIG. 6, in another embodiment, the pin 54 isdisposed on the release support 72 so as to be subjected to shear forcesby the second end 70 of the contact arm 66. In the example of FIG. 6,the shear pin 54 is securely fastened to the release support 72 andextends upwardly therefrom. The second end 70 of the contact arm 66 hasan extension 73 which extends into contact with the pin 54 adjacent theconnecting point of the pin 54 to the release support 72 so as to exerta shearing force on the pin 54 at its connection to the release support72. As in the other embodiments of the release means 40, the relativepositioning of the shear pin 54 and contact arm extension 73 should beadjustable and adjusted to hold the valve 24 securely in the closedposition until the torque exerted on the valve exceeds the selectedmagnitude at which the pin 54 should shear and the valve should open.

Referring to the example of FIG. 7, in a more preferred embodiment, therelease means 40 includes a magnetic catch 74. The magnetic catch 74 hasa first magnetic element 76 located on the second end 70 of the contactarm 66 and a second magnetic element 78 located on the release support72. The first and second magnetic elements 76, 78 are oriented so thattheir magnetic attraction holds the contact arm 66 and valve 24 in theclosed position until the torque exerted on the valve 24 and shaft 38exceeds the selected magnitude. The first and second magnetic elements76, 78 may be permanent magnets or electro-magnets, although permanentmagnets are preferred. One of the first and second magnetic elements 76,78 may be a non-magnetized material which is attracted to themagnetization of the other elements 76, 78, such as a ferro-magneticmetal. As in the other embodiments of the release means 40, the locationof the first and second magnetic elements 76, 78 should be adjustable sothat the valve 24 is held securely in the closed position in order toprevent leakage of fluid around the valve and to prevent movement and/orchattering of the valve in the housing 22. The magnetic strengths of themagnetic elements 76, 78 should be selected to hold the valve in theclosed position until the torque exerted on the valve 24, shaft 38, andcontact arm 66 exceeds the selected magnitude. The magnetic catch 74provides a repeatable release means 40 which allows the valve 24 to berestored to the closed position without replacement parts and which maybe used many times without losing any accuracy in the amount of torqueor fluid pressure required to move the valve 24 from the closed positionto the open position.

Referring to the example of FIGS. 2 and 3, in the prototype assembly 20,which is a pressure relieving device, the conversion means 36 isprovided by the valve 24 and the mounting means 26 is provided by theshaft 38. The preferred conversion means 36 applies greater force of thefluid pressure to the valve 24 on one side of the rotational axis 28 ofthe shaft 38. The conversion means 36 may be any valve placement, valveshape, valve seat shape or structure, housing shape or structure, fluidpassageway 50 shape or structure, or the like, which applies the fluidpressure in the housing inlet 46 to the valve 24 in such a manner as tocreate a moment or torque about the rotational axis 28 of the valve 24and/or shaft 38. In the prototype assembly 20, this is accomplished byusing a butterfly or disk valve 24 and mounting the valve 24 foreccentric rotation in the passageway 50. The rotational axis 28 of theshaft 38 and valve 24 is offset from the diameter 84 of the valve 24.The portion of the valve 24 on the first side 100 of the rotational axis38 is larger and has greater area exposed to the inlet fluid pressurethan the portion of the valve 24 on the second side 104 of therotational axis 28. This creates a moment and torque about therotational axis 28 and shaft 38. This arrangement has another advantagein that the shaft 38 partially balances the fluid pressure on eitherside of the rotational axis 28 and shaft 38 and therefore reduces thepressure which the valve 24 must directly resist to seal, therebyreducing the chatter or simmer experienced in some types of pressurerelieving valves, such as right angle relief valves.

Referring to example FIGS. 8-15, a more preferred embodiment of therotatable valve assembly 20 will now be discussed. Referring to theexample of FIGS. 13 and 14, the housing 22 includes a seating surface 86having an inner peripheral edge 88 extending around the passageway 50.In the prototype housing 22, the housing seating surface 86 is acontinuous, annular ledge or shelf extending around the fluid passageway50 at the juncture of the inlet 46 and outlet 48. The valve 24 has aseating surface 90 with an outer peripheral edge 92 extending around thevalve 24. In the closed position 32, the housing and valve seatingsurfaces 86, 90 are about coplanar and define a gap 94 between the innerperipheral edge 88 of the housing seating surface 86 and the outerperipheral edge 92 of the valve seating surface 90. In the open position34 of the valve 24, and when the valve 24 is in other positions than theclosed position 32, the housing and valve seating surfaces 86, 90 arenot coplanar, as best seen in FIG. 10. Preferably, the housing seatingsurface 86 and valve seating surface 90 are on the inlet side of thehousing and valve. They may be located on the outlet side.

The assembly 20 includes a seal 96 for sealing the gap 94 between theseating surfaces 86, 90 and preventing fluid flow through the valve 24and passageway 50 in the closed position 32 of the valve 24. Thepreferred seal 96 has a first portion 98 secured to the housing seatingsurface 86 on a first side 100 of the rotational axis 28 and extendingacross the gap 94 toward the valve seating surface 90; a second portion102 secured to the valve seating surface 90 on a second side 104 of therotational axis 28 and extending across the gap 94 toward the housingseating surface 86; a first transitional portion 106 coinciding with therotational axis 28 (FIG. 11); and a second transitional portion 108coinciding with the rotational axis (FIG. 11).

Referring to FIG. 12, the seal 96 is unsecured to the housing 22 andvalve 24 in the transitional portions 106, 108 so that the seal may flexor move in the transitional portions 106, 108 as the valve 24 rotatesbetween the closed position 32 and the open position 34. In thepreferred assembly 20, the first and second portions 98, 102 of the seal96 define a seal plane 110 in the closed position 32 of the valve, andthe second portion 102 of the seal 96 moves or rotates out of the sealplane 110 with the valve 24 and valve seating surface 90 as the valve 24rotates from the closed position 32 to the open position 34, as bestseen in FIGS. 9 and 10.

Referring to the example of FIGS. 9, 10, and 12, in the more preferredembodiment of the assembly 20, the rotational axis 28 of the valve 24lies in the seal plane 110. By positioning the rotational axis 28 in theseal plane 110, the valve 24 is allowed to rotate without stretching theseal 96 (as would occur if the rotational axis was inside the anglecreated by the rotating seal second portion 102 with the seal plane 110)or causing the seal to bulge or push out of the gap 94 (as would occurif the rotational axis was outside of the angle created by the rotatingseal second portion 102 with the seal plane 110). If it is desired toreduce stretching, binding, or bunching of the seal 96 as much aspossible, the rotational axis 28 should be aligned as closely aspossible with the optimum position of the seal plane 110.

As exemplified in FIGS. 13, 14, and 30-42, the optimum position of theseal plane 110 for reducing distortion of the seal will vary dependingupon the thickness of the seal 96, the shape of the seal 96, and theshape of the housing and valve seating surfaces 86, 90. For example, inthe embodiment of FIGS. 13, 14, and 38, it is contemplated that theoptimum position of the seal plane 110 passes through the seal 96 at aposition corresponding with approximately one-half the vertical or axialdimension of the notches 130, 132 and groove 134. In the embodiments ofFIGS. 30, 34, 35, 36, 37, 39, and 40, it is contemplated that optimumposition of the seal plane 110 should be visualized as being coplanarwith the housing and valve seating surfaces 86, 90. In the embodimentsof FIGS. 31, 32, and 33, it is contemplated that the optimum position ofthe seal plane 110 will pass through the seal at a positionapproximately one-half of the vertical or axial dimension of the groovecreated by the beveled, adjacent edges 312, 314 of the valve and housingseating surfaces 86, 90. In the embodiment of FIG. 41, it iscontemplated that the optimum position of the seal plane 110 will passthrough a position corresponding with about one-half the vertical oraxial dimension of the notches 334, 340. In the embodiment of FIG. 42,it is contemplated that optimum position of the seal plane 110 will passthrough a position corresponding with approximately one-half thevertical or axial dimension of the grooves 346, 348.

Referring to FIG. 8, in the prototype assembly 20, this positioning ofthe rotational axis 28 is accomplished by constructing the mountingmeans 26 such that the shaft 38 has a first shaft end 116 rotatablydisposed in the housing 22 for rotatably connecting the valve 24 to thehousing 22 and a second shaft end 118 rotatably disposed in the housing22 for rotatably connecting the valve 24 to the housing 22, with therotational axis 28 being created and defined by the rotatableconnections of the first and second shaft ends 116, 118 with the housing22. The connections of the shaft 38 and shaft ends 116, 118, to thevalve 24 are offset axially (axially along the flow axis 120 through thefluid passageway 50) from the seal plane 110 so that the connections ofthe shaft 38 and/or shaft ends 116, 118 to the valve 24 do notphysically obstruct or interfere with the gap 94 or seal 96. This may beaccomplished by relieving or cutting out the shaft ends 116, 118 wheretheir connection to the valve 24 coincides with the gap 94 and seal 96.In the prototype apparatus, a first offset bracket 122 is connectedbetween the first shaft end 116 and the valve 24 such that the joining123 of the first offset bracket 122 to the valve 24 is offset from therotational axis; and a second offset bracket 124 is connected betweenthe second shaft end 118 and the valve 24 such that the joining 125 ofthe second offset bracket 124 to the valve 24 is offset from therotational axis, as will be discussed in greater detail below.

Referring to the example of FIGS. 13 and 14, in a preferred embodiment,the first portion 98 of the seal 96 includes an inside rim 126 extendingacross the gap 94 and contacting the valve seating surface 90 in theclosed position 32 of the valve 24, and the second portion 102 of theseal 96 includes an outside rim 128 extending across the gap 94 andcontacting the housing seating surface 86 in the closed position 32 ofthe valve 24. The first and second transitional portions 106, 108 of theseal 96 also extend across the gap 94 and sealingly contact the housingand valve seating surfaces 86, 90 in the closed position of the valve24. Referring to the example of FIGS. 13 and 14, in the preferredembodiment, the inner peripheral edge 88 of the housing seating surface86 has a notch 130 extending around the inner peripheral edge 88, theouter peripheral edge 92 of the valve seating surface 90 has a notch 132extending around the outer peripheral edge 92, and the notches form orcreate a groove 134 coinciding with the gap 94 between the seatingsurfaces 86, 90 in the closed position 32 of the valve 24. Preferably,the inside rim 126 of the first portion 98 of the seal 96 has aprotuberance 136 extending into the notch 130 in the inner peripheraledge 88 of the housing seating surface 86 and extending across thegroove 134 into sealing contact with the valve seating surface 90 in aclosed position 32 of the valve 24. The preferred outside rim 128 of thesecond portion 102 of the seal 96 has a protuberance 138 extending intothe notch 132 in the outer peripheral edge 92 of the valve seatingsurface 90 and extending across the groove 134 into sealing contact withthe housing seating surface 86 in the closed position 32 of the valve24.

Referring to FIGS. 11 and 12, preferably, the first transitional portion106 of the seal 96 has a protuberance 140 and the second transitionalportion 108 has a protuberance 142 extending into the groove 134. Theprotuberances 140, 142 make sealing contact with the notches 130, 132 inthe housing and valve seating surface 86, 90 in the closed position 32of the valve 24. In the preferred embodiment of the seal 96, the insiderim protuberance 136, outside rim protuberance 138, and transitionalportion protuberances 140, 142 form an endless or continuousprotuberance extending around the valve 24 and seal 96. In the prototypeassembly 20, the inside rim protuberance 136 remains in the notch 130 inthe inner peripheral edge 88 of the housing seating surface 86 in allpositions of the valve 24 and the outside rim protuberance 138 remainsin the notch 132 in the outer peripheral edge 92 of the valve seatingsurface 90 in all positions of the valve.

Referring to the example of FIGS. 13-15, in the prototype assembly 20,the first portion 98 of the seal 96 includes a housing retainer 148,connected to the housing 22 and the first portion 98 of the seal 96, forsecuring the first portion 98 of the seal 96 to the housing (FIG. 13);the second portion 102 of the seal 96 includes a valve retainer 150,connected to the valve 24 and the second portion 102 of the seal 96, forsecuring the second portion 102 of the seal 96 to the valve 24 (FIG.14), and the seal 96 is unsecured in the transitional portions 106, 108(FIG. 15). Preferably, the housing retainer 148 extends across the gap94 with the first portion 98 of the seal 96 connected to the housingretainer 148. The seal 96 is disposed between the housing retainer 148and the gap 94 and the housing retainer 148 biases or urges the firstportion 98 of the seal 96 into sealing contact with the housing andvalve seating surfaces 86, 90 in the closed position 32 of the valve 24.The valve retainer 150 extends across the gap 94 with the second portion102 of the seal 96 connected to the valve retainer 150 and disposedbetween the valve retainer 150 and the gap 94. The valve retainer 150biases or urges the second portion 102 of the seal 96 into sealingcontact with the housing and valve seating surfaces 86, 90 in the closedposition 32 of the valve 24. The housing retainer 148 does not contactthe valve 24. The valve retainer does not contact the housing 22.

Additional example embodiments of the seal 96 are discussed in greaterdetail below. The use of the seal 96 and housing and valve seatingsurfaces 86, 90 discussed above creates a rotatable valve assembly 20 inwhich neither the housing 22 nor the valve 24 continuously wipes ordrags against a seal as the valve is rotated. This greatly reduces thefrictional forces which must be overcome to rotate the valve 24 and alsocreates a rotatable valve assembly 20 in which the torque required toinitiate rotation of the valve assembly does not increase as the valveis left in a closed position for extended periods of time. Thepreviously described seal 96, housing seating surface 86, and valveseating surface 90 may be incorporated into virtually type of rotatablevalve assembly in which it is desired to reduce the frictional forcesrequired to open, close, or rotate the valve; and may be used withoutthe conversion means 36 and with other types of power means 30, such asmanual, hydraulic, pneumatic, and electric valve actuators. Insituations where it is acceptable for the seal 96 to stretch into or tobulge away from the seating surfaces 86, 90 in the transitional portions98, 102, the rotational axis 28 may be displaced from the seal plane110.

Referring to the example of FIG. 16-19, the assembly 20 may also includereclosure means 152, located outside the housing 22, for returning thevalve 24 to the closed position 32 after the valve 24 has been opened.The reclosure means 152 is particularly useful where the assembly 20 isused as a pressure relieving device, in that, after the excessivepressure has been relieved, the reclosure means 152 will automaticallyreturn the valve 24 to the closed position 32. It is contemplated thatthe assembly 20 and reclosure means 152 will be particularly useful withthe release means 40 having a magnetic catch 74 (FIGS. 7 and 25), inthat the reclosure means 152 will automatically, without the aid of ahuman operator, reset the magnetic catch 74 and valve 24 to the closedposition until another overpressure condition exerts torque about therotational axis 28 and shaft 38 which exceeds the selected magnituderequired to open the magnetic catch 74.

The reclosure means 152 may be any form of spring-loaded actuator,pneumatically-operated actuator, electrically-operated actuator,hydraulically-operated actuator, or weight-biased actuator. The strengthof the reclosure means 152 should be selected, in view of the torque orfluid pressure at which the release means 40 is designed to allow thevalve 24 to open, to reclose the valve 24 without interfering with thepressure relieving design or capability of the valve 24, as would beknown to one skilled in the art in view of the disclosure containedherein. The reclosure means 152 may be located at the same shaft end 52,58 as the release means 40 or at the opposite outside shaft end.

Referring to the example of FIG. 16, in one embodiment, the reclosuremeans 152 comprises a torsion spring 154 connected between the outsideend 52 of the shaft 38 and a torsion spring housing 156 connected to theoutside of the housing 22 adjacent the shaft 38.

Referring to the example of FIG. 17, in another embodiment, thereclosure means 152 includes a first magnetic element 158 having north(N) and south (S) magnetic poles disposed in the outside end 52 of theshaft 38. A second magnetic element 160 having north (N) and south (S)magnetic poles is disposed in the housing 22 or in a magnet housing 162extending from the outside of the housing 22 adjacent the shaft 38. Thefirst and second magnetic elements may be electromagnets or the like,but are permanent magnets in the preferred embodiment. The first andsecond magnetic elements 158, 160 are oriented so that like magneticpoles of the first and second magnetic elements 158, 160 bias the shaft38 and valve 24 from the open position 34 to the closed position 32after the overpressure and torque forcing the valve 24 from the closedposition to the open position has subsided.

Referring to the example of FIGS. 18 and 19, in another embodiment, thereclosure means 152 includes a reclosure arm 164 connected to andextending from the outside end 52 of the shaft 38. A counterweight 166is connected to the reclosure arm 164 for urging the shaft 38 and valve24 from the open position 34 to the closed position 32. Preferably, thereclosure arm 164 is connected to the outside end 52 of the shaft 38with a counterweight housing 168. The preferred counterweight housing168 is rotationally positionable on the shaft end 52. For example, asillustrated in FIG. 19, the counterweight housing 168 may be acylindrically shaped extension which fits over the outside end 52 of theshaft 38 and has a set screw 170, or other fastening device, forselectably securing the position of the counterweight housing 168 on theshaft end 52. The set screw 170 may be loosened and the housing 168rotated with respect to the shaft end 52 in order to adjust theorientation of the reclosure arm 164 and counterweight 166 with respectto the housing 22 and valve 24. The preferred reclosure arm 164 isadjustably connected to the counterweight housing 168 so that thedistance from the rotational axis 28 of the shaft 38 to thecounterweight 166 may be adjusted in order to adjust the magnitude ofthe force or torque the counterweight 166 exerts in biasing the valve 24towards the closed position 32. In the example FIG. 19, the reclosurearm 164 extends through a slot or other transverse (to the rotationalaxis 28) passageway 172 through the housing 168 and a second set screw174 is adjustably extendable through the housing 168 into contact withthe reclosure arm 164 to secure the arm 164 in a selected position.Preferably, the counterweight 166 is detachable from the reclosure arm164 so that various sizes or weights of counterweights 166 may be usedto adjust the force or torque with which the reclosure arm 164 biasesthe valve 24 from the open position 34 towards the closed position 32.

To enable a better understanding of the invention, elements, components,and additional embodiments of the assembly 20 will now be described ingreater detail. Referring to the example of FIG. 20, the release means40 includes a pin or beam 54 connected between the shaft 38 and thehousing 22 and having an unsupported area 180 extending between theshaft 38 and the housing 22. The unsupported area 180 reduces the torqueor force magnitude required to deform or rupture the pin 54 to amagnitude below the torque or force magnitude required to shear the pin54. It is contemplated that the predictability of the force required torupture the pin 54 becomes more accurate or reliable as the length ofthe unsupported area 180 increases.

The pin 54 extends about diametrically through a hole 184 in the outsideend 52 of the shaft 38. A support housing 186 is connected to thehousing 22 around the outside end 52 of the shaft 38. The supporthousing 186 includes a slot or hole 188 which may be aligned with atleast one end of the pin 54 so that an end of the pin 54 may be extendedthrough both the shaft 38 and support housing 186 in order to lock orsecure the valve 24 in the closed position 32. The pin 54 and theunsupported area 180 between the outside end of the shaft 38 and theadjacent support housing 186 should be selected or sized so that the pin54 will rupture when a preselected magnitude of torque is applied to thevalve 24 and shaft 38. The support housing 186 and pin 54 may bedesigned so that the pin 54 passes through the shaft and through thesupport housing 186 on both sides of the shaft 38, as illustrated inFIG. 20, if it is desired to increase the torque required to rupture thepin 54. Also, a second support housing 190 may be provided at the secondoutside end 58 of the shaft 38 and provision made for providing pins 54,192 at both ends 52, 58 of the shaft 38 if it is desired to furtherincrease the torque required the shaft 38 and valve 24 from the closedposition 32 (FIG. 3). The relative positioning of the support housing(s)186, 190 and slot(s) 184, 188 should be adjustable to ensure snugengagement of the pin 54 in the slot(s) and to thereby securely hold thevalve 24 in the closed position 32 at torques below the desired rupturetorque, as would be known to one skilled in the art in view ofdisclosure contained herein.

Referring to the example of FIGS. 21 and 22, in another prototypeembodiment of the release means 40, the release support 72 includes aframe 194 connected to the outside 56 of the housing 22. A deformable orrupturable pin 54 is mounted on the release support 72 at a point spacedaway from the rotational axis 28 of the valve 24. A contact arm 66 has afirst end 68 connected to the outside end 52 of the shaft 38 and asecond end 70 which extends away from the shaft end 58 and contacts thepin 54 at a deformation initiation point 182. In the prototype assembly20, the pin 54 is simply supported, i.e., the first and second ends 196,198 of the pin 54 are supported with the deformation initiation point182 and the remainder of the pin 54 being unsupported. The pin 54 andthe distance between the supported ends 196, 198 of the pins should beselected or sized to rupture or deform when the selected torque existson the shaft 38 and arm 66. The placement of the release support 72 anddistance of the deformation initiation point 182 from the rotationalaxis 28, and the length of arm 60 may also be sized or selected inconjunction with the strength of the pin 54 to allow the valve 24 andshaft 38 to rotate when the fluid pressure exerts a predeterminedmagnitude of torque on the valve 24 and shaft 38. A second releasesupport, second contact arm, etc. may be provided at the second outsideend 58 of the shaft 28 (not illustrated) if desired or necessary for aspecific application, as would be known to one skilled in the art inview of the disclosure contained herein.

In the prototype embodiment, referring to the example of FIGS. 21-23,the second end 70 of the arm 66 contacts a lever arm 200 which extendsbetween the contact arm 66 and pin 54 in order to further increase themechanical advantage at the location of the pin 54 and reduce thestrength of the pin 54 necessary to hold the valve 24 in the closedposition 32. This is particularly useful when the assembly 20 is to beused in high pressure applications. Although the lever arm 200 may takevarious shapes and configurations to adapt to a specific situation, aswill be known to one skilled in the art in view of the disclosurecontained herein, and as further discussed below, in the prototypeassembly 20 of FIGS. 21-23, the lever arm 200 is generally L-shaped. Thelever arm 200 has a short leg 202 which contacts the arm 66 and a longleg 204 which extends perpendicularly from the short leg 202 intocontact with the pin 54. The release support 72 includes a positionadjustment mechanism 206, such as a set screw, threaded bolt, or thelike, for adjusting the position of pin 54 and the engagement betweenthe pin 54 and lever arm 200. The pin's position should be adjusted sothat the valve 24 is held sealingly engaged with the housing 22 untilthe torque about shaft 38 exceeds the desired rupture torque at whichthe valve 24 is to open.

A hinge pin 208 extends through juncture of the short and long legs 202,204 and creates an axis of rotation of the lever arm 200 which is aboutperpendicular to the plane of the lever arm 200. The hinge pin 208 hasreceptacle 210 (FIG. 21) which connects the hinge pin 208 to the outsideof the housing 22. In the prototype lever arm 200, the free end 212 ofthe long leg 204 has a pointed, knife-like edge which contacts the pin54 at the deformation initiation point 182 (FIG. 23). As previouslymentioned, the pin 54 may be selected to rupture or to deform (i.e.,bend) when subjected to a preselected force, thereby freeing the arm 66and allowing the arm 66, shaft 38, and valve 24 to rotate to the openposition 34 of the valve 24. In the prototype assembly 20, a handle 214is provided for lifting or carrying the assembly 20, as the assembly 20may be large and heavy. As indicated in FIG. 22, replacement pins 216may be stored in the handle 214.

FIGS. 24-28 exemplify a more preferred embodiment of the release means30, which does not require a housing 22 as large as the previouslydiscussed embodiments, particularly along the flow axis 120. In theembodiments of FIGS. 24-28, the contact arm 66 has a first end 68connected to the outside end 52 of the shaft 38 and a second end 70extending therefrom. The release means 40 includes stanchion 222extending from the outside 56 of the housing 22. Lever arm 224 ispivotably connected to the stanchion 222 so that the lever arm 224 willpivot in a plane about parallel with the pivotal plane of the contactarm 66, the pivotal plane of the lever arm 224 being closer to thehousing 22 so that the lever arm 224 is free to pivot between thecontact arm 66 and the housing 22. The lever arm 224 has a first end 226extending away from the stanchion and shaft 38 and a second end 228extending from the stanchion 222 toward the shaft 38, the distance fromthe stanchion 222 to the second end 228 being greater than the distanceto the first end 226. A post 230 extends from one of the second end 70of the contact arm 66 or the first end 226 of the lever arm 224 intocontact with the other (in the prototype assembly 20 the post is fixedlyattached to the second end 70 of the contact arm 66). A release support72 is connected to the housing 22 through the contact arm 66 and shaft38, i.e., the release support 72 is connected to the contact arm 66 nearthe first end 68 of the contact arm 66 and between the shaft 38 and thestanchion 222, such that the release support 72 is in the rotationalpath of the second end 228 of the lever arm 224. As the shaft rotates,the post 230 moves the first end 226 of the lever arm 224, and therotatable connection of the lever arm 224 to the stanchion 222 acts as afulcrum in transmitting the motion of the post 230 and first end 226 tothe second end 228 of the lever arm 224. The second end 228 of the leverarm 224 is in contact with a pin, spring, or magnet disposed on therelease support and which is selected in conjunction with the sizing ofthe contact arm 66 and lever arm 224 to restrain rotation of the shaft38 until the torque about the rotational axis 28 and shaft 38 exceeds aselected magnitude. As in the embodiments of the release means 40 ofFIGS. 2-7 and 20-22, in the embodiments of FIGS. 24-28, the variousforms of the pin, spring, and magnet should be secured to the contactarm 66 and/or release support 72 so that the release means 40 does notinterfere with the rotation of the contact arm 66, lever arm 224, andvalve 24 from the closed position to the open position when the torqueexerted on the shaft 38 and release means 40 exceeds the selectedmagnitude; and the relative positioning of the pin, spring, magnet,contact arm 66, and lever arm 224 should be adjustable and adjusted tohold the valve 24 securely in the closed position until the torqueexerted on the shaft 38 exceeds the selected magnitude.

Referring to the example embodiment of FIG. 25, a first magnetic element76 is connected to the release support 72 and a second magnetic element78 is connected to the second 228 of the lever arm 224, the attractionof the magnetic elements preventing the second end 228 of the lever arm224 from rotating (counterclockwise in FIG. 25) away from the releasesupport housing 232 until the torque about shaft 38 (clockwise in FIG.25) exceeds a preselected magnitude.

Referring to the example embodiment of FIG. 26, the release support 72supports a pin 54 which prevents the second end 228 of the lever arm 224from rotating (counterclockwise in FIG. 26) and allowing the shaft 38 torotate (clockwise in FIG. 26) until the torque about the shaft 38exceeds a preselected magnitude and breaks the pin 54. The pin 54 may besimply supported or cantilevered on the release support 72. If the pin54 is cantilevered, the release support 72 may be eliminated bycantilevering the pin 54 from the contact arm 66 into obstruction withthe second end 228 of the lever arm 224, as indicated by the solid linedrawing of the pin 54 in FIG. 26.

Referring to the example embodiment of FIG. 27, a tension pin or wire234 has a first end 236 connected to the release support 72 and a secondend 238 connected to the second end 228 of the lever arm 224 such that(clockwise) rotation of the shaft 38 is restrained by the tensilestrength of the tension pin 234 until the torque about the shaft 38exceeds the tensile strength of the wire 234 and breaks the wire 234.The tension pin 234 may be replaced with a tension spring 234, as wouldbe known to one skilled in the art in view of the disclosure containedherein. The tension spring 234 would have the advantage of automaticallyand repeatably restoring the valve 24 to the closed position withoutreplacement parts.

Referring to the example of FIG. 28, a buckling pin 240 has a first end242 connected to the release support 72 and a second end 244 connectedto the second end 228 of the lever arm 224 such that any rotation(clockwise) of the shaft 38 and valve 24 toward the open position 34places the buckling pin 240 in compression. The compressive strength ofthe buckling pin 240 is selected to resist the rotation of the shaft 28until the torque exceeds the selected magnitude and buckles or bends thepin 240. The buckling pin 240 may be replaced with a compression spring240, as would be known to one skilled in the art in view of thedisclosure contained herein. The compression spring 240 would have theadvantage of repeatably restoring the valve 24 to the closed positionwithout replacement parts.

Referring to the example of FIGS. 1 and 10, the housing 22 may be ofintegral, one piece construction, or assembled of components, e.g., theinlet 46 and outlet 48 may be separate components. The housing 22 mayalso be an integral part of the fluid pressure source, although thepreferred assembly 20 is an independent device. In the prototypeassembly 20, the inlet 46 and outlet 48 have a common, co-linear axis120, as exemplified in FIGS. 1 and 9, although the housing 22 may becurved or angled, as would be known to one skilled in the art in view ofthe disclosure contained herein.

The housing 22 and valve 24 should be shaped to facilitate at least 90degrees of rotation by the valve 24 (as exemplified in FIGS. 1 and 16)without interfering with the movement of the valve 24. In the prototypeassembly 20, the fluid passageway 50 is about circular when viewedaxially (as seen in FIGS. 3 and 8), and the valve 24 has a perimeter ofabout the same shape as the fluid passageway 50. Preferably the innerperipheral edge 88 of the housing seating surface 86 and the outerperipheral edge 92 of the valve seating surface 90 are both aboutcircular when viewed along the flow axis 120.

Referring to the example of FIG. 8, as previously discussed, in the morepreferred embodiment of the assembly 20, the mounting means 26 includesfirst shaft end 116 and second shaft end 118 which rotatably connect thevalve 24 to the housing 22 and which define the rotational axis 28 ofthe valve 24. The rotational axis 28 is offset transversely from thediametrical axis 84 of the valve 24 by the positioning of the first andsecond shaft ends 116, 118 so that the fluid force in the inlet 46 ofthe housing 22 will create torque about the rotational axis 28, aspreviously discussed. The first and second shaft ends 116, 118 do notextend into the fluid passageway 50. First and second offset brackets122, 124 extend through slots 250, 252 in the housing between the firstand second shaft ends 116, 118 and fluid passageway 50. The slots 250,252 allow the first and second offset brackets 122, 124 to transmitrotation of the valve 24 to the first and second shaft ends 116, 118 andto the outside end 52 of the shaft 38. As previously discussed, theoffset brackets 122, 124 also position the valve 24 so that therotational axis 28 of the shaft 38 and shaft ends 116, 118 lie in theseal plane 110, as seen in FIG. 9, so that the rotation of the valve 24does not buckle or stretch the seal 96. The preferred offset brackets122, 124 and disk bracket 254 are connected to the outlet side of thevalve 24 (to the opposite side of the valve 24 from the seal 96 andvalve seating surface 90) to allow alignment of the rotational axis 28with the seal plane 110 while removing the shaft 38 and shaft ends 116,118 from interference with the seal 96.

The disk bracket 254 is welded to the outlet side of the valve 24. Thedisk bracket 254 has opposite ends 253, 255 which extend off of thevalve 24. The offset brackets 122, 124 are welded to the opposite ends253, 255 of the disk bracket 254, in the prototype assembly 20. A firststop 246 extends from the first end 253 of the disk bracket 254 betweenthe slot 250 and the valve 254 in such a manner that the first stop 246contacts the housing 22 when the valve 24 reaches the open position. Abumper 247 of resilient material is connected to the housing 22 in sucha position as to receive the stop 246 when the valve 24 reaches the openposition and to cushion the impact of the stop 246 hitting the housing22. A second stop 248 extends from the second end 255 of the diskbracket 254 between the second offset bracket 124 and the valve 24 and acorresponding second bumper 249 is provided on the housing 22 in theprototype assembly 20.

Referring to the example of FIG. 10, the preferred seal 96 and sealplane 110 are on the inlet 46 side of the valve 24. The transverseoffset of the rotational axis 28 from the diameter 84 of the valve 24creates the fluid force imbalance and torque about the rotational axis28. The rotational axis 28 passes through the valve 24 and seal 96 in aposition which creates a larger first side 100 of valve 24 and firstportion 98 of the seal 96; and a smaller second side 104 of valve 24 andsecond portion 102 of the seal 96. Since the fluid pressure exertsgreater force on the valve 24 on the larger first side 100 of the valve24, the larger first side 100 of the valve 24 is pushed towards theoutlet 48 of the housing 22, thereby defining the direction of rotationof the valve 24. By securing the first portion 98 of the seal 96 to thehousing seating surface 86, the first portion 98 of the seal 96 remainson the housing seating surface 86 and is not pushed through the housing22 as the valve 24 rotates. Similarly, since the second portion 102 ofthe seal 96 is secured to the valve seating surface 90 which rotatestowards the inlet, the second portion 102 of the seal 96 also rotatesfrom the closed position 32 to the open position 34 without dragging orwiping against the housing 22. It is intended to be understood that,although not the preferred embodiment and not illustrated, the housingseating surface 86, valve seating surface 90, and seal 96 may be placedon the outlet side of the valve with the offset brackets 122, 124connected to the inlet side of the valve 24 in such a manner that theseal 96 will not drag or wipe against the housing 22 or valve 24 and theother benefits of the invention will be achieved, as would be known toone skilled in the art in view of the disclosure contained herein.

Referring to the example of FIG. 11, a view of the inlet face 292 orside of the prototype seal 96 which is placed against the housing andvalve seating surfaces 86, 90 will now be described. The seal 96 has alarger, or circumferentially longer, first portion 98, acircumferentially shorter second portion 102, and first and secondtransitional portions 106, 108. The first portion 98 includes a web 257for connecting the first portion to the housing seating surface 86,protuberance 136, and inside rim 126 which extends across the gap 94 forcontacting the valve seating surface 90. The web 257 may be described asextending radially outwardly from the protuberance 136 and having a lip276 which assists in securing the first portion 98 of the seal to thehousing seating surface 86. The second portion 102 of the seal may bedescribed as having an outside rim 128 which extends across to gap 94for contacting the valve seating surface 90, protuberance 138, and a web259 which extends radially inwardly from the protuberance 138. The web259 includes a lip 96 which assists in securing the second portion 102to the valve seating surface 90. As previously discussed, the rotationalaxis 28 of the valve 24 passes through the transitional portions 106,108 of the seal 96 and therefore the radial sides of the protuberance140, 142 in the transitional portions 106, 108 are free of radiallyextending material so that the seal may bend or flex in the transitionalportions 106, 108 without interference. As previously mentioned, theseal is unsecured to the valve 24 or housing 22 in the transitionalportions 106, 108. The transitional portions 106, 108 should extendcircumferentially on either side of the rotational axis 28 sufficientlyto allow the seal 96 and valve 24 to rotate without interference. Asseen in FIG. 11, preferably the protuberance 136 of the first portion98, protuberance 138 of the second portion 102, protuberance 140 of thefirst transitional portion 106, and protuberance 142 of the secondtransitional portion 108 form an endless, continuous protuberance. Theweb 257 of the first portion 98 has radial slots 256 and the web 259 ofthe second portion 102 has radial slots 258 which are cut into the webs257, 259 to allow the seal material to be joined into an endless sealwithout binding or bunching.

FIG. 29 is a cross section of the extruded strip 260 of elastomermaterial which is joined end-to-end to form the seal 96. As is seen inFIG. 29, the extruded strip 260 has a central protuberance 262 withsymmetrical radial extensions 264, 266 extending from each side of theprotuberance 262. To make the seal 96 of FIG. 11, the length of thefirst portion 98 of the seal 96 is measured along the centralprotuberance 262, the length of the transitional portion 106 is measuredand added, the length of the second portion 102 is measured and added,and the length of the second transitional portion 108 is measured andadded. The strip 260 is cut at that length. The radial extension 264,266 from the central protuberance 262 opposite the web 257 (FIG. 11) ofthe first portion is removed, the radial extension 264, 266 on bothsides of the protuberance in the first transitional portion 106 isremoved, the radial extension 264, 266 opposite the web 259 (FIG. 11) ofthe second portion 98 is removed; the radial extensions 264, 266 areremoved in the second transitional portion 108, the slots 256, 258 arecut in the webs 257, 259, and the ends of the protuberance 262 arebonded together to form the seal 96. It is contemplated that the sealmay also be formed by injection molding and other known methods. Theseal 96 is preferably made of a resilient material suitable for thefluids which will be in contact with the seal 96, such as one of theelastomers commonly used in making o-rings and other resilient seals, aswould be known to one skilled in the art in view of the disclosurecontained herein.

FIG. 13 is an enlarged detail drawing of the radial cross section of thefirst portion 98 of the seal 96 and housing retainer 148, as marked onFIG. 9. The first portion 98 of seal 96 may be described as having aninside rim 126, outside rim 270, inlet face 272, and outlet face 274.The protuberance 136 extends from the outlet face 274 into the groove134 in order to seal the gap 94 between the housing 22 and valve 24. Inthe prototype assembly 20, the vertical or axially extending walls ofthe notches 130, 132 form an angle of approximately one degree from aperpendicular to the seal plane 110, and diverge towards the inlet 46 tofacilitate entry and exit of the protuberance 136 from the groove 134.Lip 276 extends from the outlet face 274 into an arcuate groove 278 inthe housing seating surface 86. The groove 278 extends entirely andendlessly around the housing 22 and valve 24 in the prototype assembly20. The lip 276 and groove 278 help secure the seal 96 to the housingseating surface 86. Other than the lip 276, the outside rim 270 is offlat, arcuate construction. The inlet face 272 of the seal 96 is flatand planar across the inside and outside rims 126, 270. The housingretainer 148 may be described as having an inside segment 280, outsidesegment 282, contact face 284, and exposed face 286. In the embodimentof FIG. 13, the housing retainer 148 is rectangular in cross section andextends across the radial dimension of the inlet face 272 of the seal96. Screws 288 extend through the housing retainer 148 and seal 96between the lip 276 and protuberance 136 in order to secure the housingretainer 148 and seal 96 to the housing 22. The housing retainer 148does not extend into the first and second transitional portions 106, 108(FIG. 15) of the seal 96, as previously discussed.

FIG. 14 is an enlarged detail drawing of the radial cross section of thesecond portion 102 of the seal 96 and valve retainer 150 as marked onFIG. 9. The second portion 102 of the seal 96 may be described as havingan outside rim 128, inside rim 290, inlet face 292, and outlet face 294.The protuberance 138 extends from the outlet face 294 into the groove134 in order to seal the gap 94 between the housing 22 and valve 24. Inthe prototype assembly 20, the vertical or axially extending walls ofthe notches 130, 132 form an angle of approximately one degree from aperpendicular to the seal plane 110, and diverge towards the inlet 46 tofacilitate entry and exit of the protuberance 138 from the groove 134.Lip 296 extends from the inside rim 290 of the inlet face 292 into anarcuate groove 298 in the valve seating surface 90. The groove 298extends entirely and endlessly around the valve 24 in the prototypeassembly 20. The lip 296 and groove 298 help secure the seal 96 to thevalve seating surface 90. Other than the lip 296, the inside rim 290 isof flat, arcuate construction and connects the lip 296 to theprotuberance 138. The inlet face 292 of the second portion 102 of theseal 96 is flat and planar across the inside and outside rims 290, 128.The valve retainer 150 may be described as having an inside segment 300,outside segment 302, contact face 304, and exposed face 306. In theembodiment of FIG. 14, the valve retainer 150 is rectangular in crosssection. The outside segment 302 extends entirely across the radialdimension of the inlet face 292 of the second portion 102 of the seal 96and the inside segment 300 extends off of the seal 96 and onto the valveseating surface 90. The valve seating surface 90 is relieved or cut outso that the exposed face 306 of the inside segment 300 of the valveretainer 150 is coplanar with the surface of the valve 24. The insidesegment 300 of the valve retainer 150 is secured to the valve 24 withscrews 288, which do not pass through the seal 96. The valve retainer150 does not extend into the first and second transitional portions 106,108 (FIG. 15) of the seal 96, as previously discussed. The screws 288 onthe housing retainer 148 of FIG. 13 extend through the outside rim 270of the first portion 98 of the seal 96 (rather than not passing throughthe seal 96 as do the screws 288 of the second portion 102 illustratedin FIG. 14) to accommodate the physical restraints imposed by thestructure of the housing 22.

The following FIGS. 30-42 present various embodiments of the seal 96. Tosimplify the explanation, a cross-sectional view of only the secondportion 102 of each embodiment of the seal 96 and valve retainer 150 areillustrated. It is intended to be understood that all embodiments of theseal 96 will be unretained or unsecured in the first and secondtransitional portions 98, 102 and that the unillustrated first portions98 are essentially the mirror image of the illustrated second portions,although, as with the embodiments of FIGS. 13 and 14, structural changesmay be made in the first portions 98 to accommodate space limitations onthe housing 22 and housing seating surface 86, as would be known to oneskilled in the art in view of the disclosure contained herein. It shouldalso be understood that in all embodiments of the seal, the housingretainer 148 and/or valve retainer 150 may be supplemented with achemical bonding of the appropriate portion of the seal 96 to thehousing 22, valve 24, and/or the retainers 148, 150; and the retainers148, 150 may be replaced by chemical bonding of the seal 96 to theappropriate one of the housing 22 or valve 24.

In the embodiment of FIG. 30, the seal 96 is about retangular in crosssection. The outside rim 128 of the seal 96 extends across the gap 94onto the housing seating surface 86, and the inside rim 290 of the seal96 extends across the gap 94 onto the valve seating surface 90. Theinside segment 300 of the valve retainer 150 is fastened directly to thevalve seating surface 90 with screws 288. The contact face 304 of theoutside segment 302 of the valve retainer 150 is relieved to form a slotin the valve retainer 150 which receives the inside rim 290 of the seal96 for fastening seal 96 to the valve seating surface 90. The outsidesegment 302 of the valve retainer 150 extends from the valve seatingsurface 90 to approximately the center of the gap 94.

In the embodiment of FIG. 31, the edge 312 of the valve seating surface86 and the adjacent edge 314 of the housing seating surface 90 arebeveled to create a generally v-shaped notch above the gap 94 in theclosed position 32 of the valve 24. The outside rim 128 of the seal 96is circular in cross section and sized such that the center of thecircular outside rim 128 is aligned with the gap 94 and about coplanarwith the housing and valve seating surfaces 86, 90 in the closedposition 32 of the valve 24. The inside rim 290 of the seal 96 isgenerally rectangular in cross section, is smaller in its axialdimension than the radius of the circular outside rim 128, and extendseccentrically from the circular outside rim 128 with the outlet face 294of the inside rim 290 about aligned with the center of the circularoutside rim 128. The inside rim 290 is fastened directly to the valveseating surface 90 with screws 288.

In the embodiment of FIG. 32, the adjacent edges 312, 314 of the housingand valve seating surfaces 86, 90 are beveled to form a generallyv-shaped notch above the gap 94. The outside rim 128 of the seal 96 iscircular in cross section and is positioned such that the center of thecircular outside rim 128 is aligned with the gap 94. The inside rim 290of the seal 96 is generally rectangular in cross section with its longeraxis aligned with the center of the circular outside rim 128 andextending onto the valve seating surface 90. The inside rim 290 issmaller in axial dimension (vertical in FIG. 32) than the radius of thecircular outside rim 128. The contact face 304 of the valve retainer 150does not directly contact the valve seating surface 90 but restsentirely upon the inlet face 292 of the seal 96. The valve retainer 150is shaped such that both its contact face 304 and exposed face 306follow the profile of the radial cross section of the inlet face 292 ofthe seal 96 and extend across the gap on the seal 96. Screws 288 passthrough the inside segment 300 and inside rim 290 to fasten the seal 96and valve retainer 150 to the valve seating surface 90.

In the embodiment of FIG. 33, the adjacent edges 312, 314 of the housingand valve seating surfaces 86, 90 are beveled to created a v-shapednotch above the gap 94. The outside rim 128 of the seal 96 is circularin cross section with the radius of the circular outside rim 128 beinglarger than the depth of the V-shaped notch. The inside rim 290 of theseal 96 is generally rectangular in cross section with the inlet face292 extending tangentially from the outside surface of the circularoutside rim 128. The axial dimension (vertical in FIG. 33) of the insiderim 290 is less than the diameter of the circular outer rim 128 so thatthe outlet face 294 of the inside rim 290 is in contact with the valveseating surface 90 when the circular outside rim 128 is sealingly seatedagainst the adjacent edges 312, 314 of the housing and valve seatingsurfaces 86, 90. A notch 316 is formed in the inlet face 292 of the seal96 between the outside rim 128 and inside 290. The contact face 304 ofthe valve retainer 150 does not directly contact the valve seatingsurface 90 but is entirely supported by the inlet face 292 of the seal96. The contact face 304 and outlet face 306 of the valve retainer 150are parallel and are shaped to follow the profile of the inlet face 292of the seal 96 across the gap 94. Screws 288 pass through the insidesegment 300 and inside rim 290 to fasten the seal 96 and retainer 150 tothe valve seating surface 90.

In the example embodiment of FIG. 34, the outside rim 128 and inside rim290 of the seal 96 are both circular in cross section and havesubstantially the same radius. The seal 96 is positioned such that thecircular outside rim 128 and circular inside rim 290 contact theirrespective housing and valve seating surfaces 86, 90 about equidistantlyfrom the gap 94. The inlet face 292 of the seal 96 extends tangentiallyto the outside surfaces of the circular outside and inside rims 128, 290and forms a web 318 connecting the outside and inside rims 128, 290. Theweb 318 is smaller in axial dimension than the diameter of the circularoutside and rims 128, 290. The contact face 304 of the outside segment302 of the valve retainer 150 has substantially the same shape as theprofile of the inlet face 292 of the seal 96 and extends across the gap94 on the seal 96. The remainder of the outside segment 302 is generallyrectangularly shaped. The contact face 304 of the inside segment 300 ofthe valve retainer 150 directly contacts the valve seating surface 90and a screw 288 passes through the outside segment 302 without passingthrough the seal 96.

In the example embodiment of FIG. 35, the outside and inside rims 128,290 of the seal 96 are both circular in cross section and haveapproximately the same radius. The inlet and outlet faces 292, 294 ofthe seal 96 between the outside and inside rims 128, 290 form aconnecting web 318 which is smaller in axial dimension than the diameterof the circular rims 128, 290 and which is positioned substantiallycloser to the seating surfaces 86, 90 than to the opposite extremity ofthe rims 128, 290. The seal 96 is positioned so that the outside andinside rims 128, 290 are approximately equidistantly spaced from the gap94. The contact face 304 of the outside segment 302 of the valveretainer 150 has a ridge 320 extending axially therefrom which contactsthe inlet face 292 of web 318. The circular rims 128, 290 contact inletface 304 on either side of the ridge 320. The outside segment 302extends completely across both rims 128, 290 of the seal 96. The insidesegment 300 of the valve retainer 150 is fastened directly to the valveseating surface 90 with screws 288 which do not pass through the seal96.

Referring to example FIG. 36, the housing seating surface 86 has ahousing groove 322 spaced away from the gap 94 and the valve seatingsurface 90 has a valve groove 324 spaced away from the gap 94. Thehousing groove 322 creates a housing landing area 326 and the valvegroove 324 creates an adjacent valve landing area 328 which contact theoutlet face 294 of the seal 96 on either side of the gap 94. The seal 96is generally rectangular in cross section and the outside rim 128extends over groove 322 with the inside rim 290 extending over groove324. The inside segment 300 of the valve retainer 150 is connecteddirectly to the valve seating surface 90 with a screw 288 which does notpass through seal 96. The contact face 304 at the outside segment 302 ofvalve retainer 150 is shaped to follow the profile of the inlet face 292of the seal 96.

Example FIG. 37 differs from the embodiment of FIG. 36 only in that theseal 96 and valve retainer 150 are both rectangular in cross section andthe screw 288 or equivalent fastener passes through both the valveretainer 150 and seal 96.

In the embodiment of FIG. 38, the housing seating surface 86 and valveseating surface 96 have notches 130, 132 which form groove 134, aspreviously discussed (FIGS. 13 and 14). The seal 96 has a protuberance326 which extends from the outlet face 294 into the groove 134. Theinlet face 292 of the seal 96 includes a ridge 328 extending away fromthe valve seating surface 86 at the outside rim 128 and a ridge 330extending away from the valve seating surface 90 at the inside rim 290.The contact face 304 of the outside segment 302 of the valve retainer150 is shaped to contact the inlet face 292 between the ridges 328, 330and to contact the outside surfaces of ridge 330. The valve retainer 150does not extend over ridge 328 of the outside rim 128. The insidesegment 300 of the valve retainer is in direct contact with the valveseating surface 90 and the screw 288 passes directly through the insidesegment 300 without passing through seal 96.

In the embodiment of FIG. 39, the seal 96 is generally shaped like apyramid in cross section with an apex 332 of the pyramid centered overthe gap 94. The inside rim 290 of the seal 96 is bonded to the valveseating surface 90 to retain the seal 96 to the valve seating surface90.

The embodiment of FIG. 40 uses the same pyramid shaped seal 96 of FIG.39. In the embodiment of FIG. 40, a valve retainer 150 is providedhaving an inside segment 300 that is fastened directly to the valveseating surface 90 with a screw which does not pass through the seal 96.The outside segment 302 of the valve retainer 150 is shaped in crosssection such that the contact face 304 and exposed face 306 are paralleland follow the contour of the pyramid shaped seal over the apex 332 ofthe seal with the outside segment 302 extending over the gap 94 but notextending beyond the outside rim 128 of the seal 96.

In the embodiment of FIG. 41, the housing seating surface 86 has a notch334 adjacent the gap 94 and a groove 336 spaced away from the notch 334,the notch 334 and groove 336 forming a ridge 338 in the housing seatingsurface 86. The valve seating surface 90 has a notch 340 adjacent thegap 94, a groove 342 spaced away from the notch 340, and a ridge 344formed between the notch 340 and groove 342. The outside rim 128 andinside rim 290 of the seal 96 extend equidistantly onto the housingseating surface 86 and valve seating surface 24 to approximately thecenter of the grooves 336, 342. The outlet face 294 of the seal 96 isshaped to complementarily fit into the notches 334, 340 and sealinglyengage ridges 338, 344. The inside rim 290 of the seal is bonded to thevalve seating surface 90.

In the embodiment of FIG. 42, a groove 346 is provided in the housingseating surface 86 and groove 348 is provided in the valve seatingsurface 90. The grooves 346, 348 are about equidistantly spaced from thegap 94. The seal 96 includes a rectangular web 350 extending between theoutside rim 128 and inside rim 290. The outside rim 128 includes aprotuberance 352 which extends into groove 346 and the inside rim 290includes a protuberance 354 which extends into groove 348. In the closedposition of the valve 24 the outlet face 294 of the seal 96 between theprotuberances 352, 354 contacts the adjacent edges of the housing andvalve seating surfaces 86, 90. The inlet face 292 of the seal 96 issubstantially flat or planar. The inside segment 300 of the valveretainer 150 is secured directly to the valve seating surface 90 with ascrew 288. The outside segment 302 extends across the gap to about themiddle of the groove 346 in the housing seating surface 86. The contactface 304 of the outside segment 302 is relieved or cut out and contouredto receive the inlet face 292 of the seal 96. Preferably, the seal 96 isbonded to the outside segment 302 of the valve retainer 150.

Referring to the example of FIG. 43, the assembly 20 may include vacuumrelief means 356 for sensing a vacuum in the housing inlet 46 andopening a flow passageway 358 between the inlet 46 and outlet 48 of thehousing 22 in order to relieve the vacuum. In the example of FIG. 43,the flow passageway 358 passes through and is located in the valve 24.The flow passageway has an inlet 360 and an outlet 362 correspondingwith the inlet 46 and outlet 48 of the housing 22. A diaphragm 364 oflarger diameter than the flow passageway 358 extends across and sealsthe inlet 360 of the flow passageway. A spring frame 366 is connected tothe outlet side of the valve 24 and supports a spring 368 which holdsthe diaphragm 364 in sealing contact with the inlet side of the valve24. Normally, the positive fluid pressure in the inlet 46 of the housingand the spring 368 force the diaphragm 364 into sealing engagement withthe valve 24. If a negative pressure drop (a greater pressure on theoutlet 48 side of the valve than the inlet 46 side of the valve) or avacuum in the inlet 46 of the housing 22 develops while the valve 24 isin the closed position, the spring 368 will allow the diaphragm 364 toopen the flow passageway 358 and relieve the negative pressure drop orvacuum, thereby preventing potential damage to the seal 96. The strengthof the spring 368 is selected to provide the desired set pressure atwhich vacuum relief will begin. In the example of FIG. 43, the springframe 366 and spring 368 are inset into the valve 24 onto an annularledge 370 which is created by making the diameter of the outlet 362larger than the diameter of the inlet 360.

While presently preferred embodiments of the invention have beendescribed herein for the purpose of disclosure, numerous changes in theconstruction and arrangement of parts and the performance of steps willsuggest themselves to those skilled in the art in view of the disclosurecontained herein, which changes are encompassed within the spirit ofthis invention, as defined by the following claims.

What is claimed is:
 1. Rotatable valve assembly, comprising:a housinghaving an inlet and an outlet defining a fluid passageway through thehousing, and having an inner peripheral edge extending around the fluidpassageway; a valve located in the passageway rotatable between a closedposition and an open position, and having an outer peripheral edge, theinner peripheral edge of the housing and the outer peripheral edge ofthe valve defining a gap in the closed position of the valve, the outerperipheral edge defining a valve plane; a seal, connected to one of thevalve and the housing, for sealing the gap and defining a seal plane,the entire seal lying in the seal plane in the closed position of thevalve; mounting means for rotatably mounting the valve in the housingabout a rotational axis and including a shaft having an outside endextending through the housing, the shaft being rotatable with the valve,the rotational axis of the valve lying in the seal plane and the valveplane; conversion means for converting fluid pressure in the housinginto torque exerted on the shaft; and release means, located outside thehousing, for preventing rotation of the shaft and valve from the closedposition when the torque exerted on the shaft is below a selectedmagnitude and for releasing the shaft in order to allow rotation of theshaft and valve to the open position when the torque exerted on theshaft exceeds a selected magnitude.
 2. Assembly of claim 1 in which therelease means comprises:deformable means for making deformable contactbetween the housing and the shaft.
 3. Assembly of claim 2:wherein thedeformable means makes rupturable contact between the housing and theshaft.
 4. Assembly of claim 2:in which the mounting means includes ashaft having a second outside end extending through the housing, theshaft being rotatable with the valve; and in which the release meansincludes a second deformable means for making deformable contact betweenthe housing and the shaft.
 5. Assembly of claim 1 in which the mountingmeans comprises:a first shaft end rotatably disposed in the housing; asecond shaft end rotatably disposed in the housing, the first and secondshaft ends being aligned to define the rotational axis of the valve; afirst offset bracket connected between the first shaft end and the valvewith the joining of the first offset bracket to the valve being offsetfrom the rotational axis; and a second offset bracket connected betweenthe second shaft end and the valve with the joining of the second offsetbracket to the valve being offset from the rotational axis.
 6. Assemblyof claim 5:wherein the seal defines a seal plane in the closed positionof the valve and the rotational axis of the valve lies in the sealplane.
 7. Assembly of claim 1:wherein the conversion means is defined asapplying greater fluid force to the valve on one side of the rotationalaxis of the valve.
 8. Assembly of claim 1 in which the release meanscomprises:deformable means for making deformable contact between thehousing and the outside end of the shaft.
 9. Assembly of claim 8 inwhich the deformable means comprises:a pin, connected between thehousing and the shaft, which bends when the torque exerted on the shaftexceeds a selected magnitude.
 10. Assembly of claim 9:wherein the pin isconnected between the shaft and the housing so that the pin is placed incompression by the torque exerted on the shaft.
 11. Assembly of claim10:wherein the pin is connected between the shaft and the housing sothat the pin is placed in tension by the torque exerted on the shaft.12. Assembly of claim 10:wherein the pin is connected between the shaftand the housing so that the pin is subjected to shear forces by thetorque exerted on the shaft.
 13. Assembly of claim 8 in which thedeformable means comprises:a pin, connected between the shaft and thehousing, which breaks when the torque exerted on the shaft exceeds aselected magnitude.
 14. Assembly of claim 1 in which the release meanscomprises:a contact arm, having a first end connected to the outside endof the shaft and a second end extending from the shaft; a releasesupport connected to the housing; and a pin connected to the releasesupport and obstructing rotation of the second end of the contact arm,shaft, and valve from the closed position of the valve until the torqueexecuted on the shaft exceeds a selected magnitude.
 15. Assembly ofclaim 14:wherein the pin is disposed on the release support so as to besubjected to compressive forces by the contact arm.
 16. Assembly ofclaim 14:wherein the pin is disposed on the release support so as to besubjected to shear forces by the contact arm.
 17. Assembly of claim14:wherein the pin is connected between the release support and thecontact arm so as to be placed in tension by the contact arm. 18.Assembly of claim 1 in which the release means comprises:a contact armhaving a first end connected to the outside end of the shaft and asecond end extending from the shaft; a release support connected to thehousing; a magnetic catch having a first magnetic element located on thecontact arm and a second magnetic element located on the releasesupport, the magnetic attraction between the first and second magneticelements preventing rotation of the contact arm, shaft, and valve fromthe open position.
 19. Assembly of claim 1, comprising:reclosure means,located outside the housing, for returning the valve to the closedposition after the valve has been opened.
 20. Assembly of claim 19 inwhich the reclosure means comprises:a torsion spring connected betweenthe outside end of the shaft and the housing.
 21. Assembly of claim 19in which the reclosure means comprises:a first magnetic media havingmagnetic poles disposed in the outside end of the shaft; and a secondmagnetic media having magnetic poles disposed in the housing, the firstand second magnetic media being oriented so that the like magnetic polesof the first and second magnetic media bias the shaft and valve from theopen position to the closed position.
 22. Assembly of claim 19 in whichthe reclosure means comprises:a reclosure arm connected to and extendingfrom the outside end of the shaft; and a counterweight, connected to thearm, for urging the shaft and valve from the open position to the closedposition.
 23. Valve assembly of claim 1, wherein:the seal is connectedto the valve.
 24. Valve assembly of claim 1, wherein:the seal isconnected to the housing.
 25. Rotatable valve assembly, comprising:ahousing having an inlet and an outlet defining a fluid passagewaythrough the housing, and having an inner peripheral edge extendingaround the fluid passageway; a valve located in the passageway,rotatable between a closed position and an open position, and having anouter peripheral edge, the inner peripheral edge of the housing and theouter peripheral edge of the valve defining a gap in the closed positionof the valve, the outer peripheral edge defining a valve plane; a seal,disposed in the gap, for sealing the gap and defining a seal plane, theentire seal lying in the seal plane in the closed position of the valve;mounting means for rotatably mounting the valve in the housing about arotational axis and including a shaft having an outside end extendingthrough the housing, the shaft being rotatable with the valve, therotational axis of the valve lying in the seal plane and the valveplane; conversion means for converting fluid pressure in the housinginto torque exerted on the shaft; and release means, located outside thehousing, for preventing rotation of the shaft and valve from the closedposition when the torque exerted on the shaft is below a selectedmagnitude and for releasing the shaft in order to allow rotation of theshaft and valve to the open position when the torque exerted on theshaft exceeds a selected magnitude.
 26. Valve assembly of claim 25,wherein:the seal is connected to the valve.
 27. Valve assembly of claim25, wherein:the seal is connected to the housing.